nix-profile-daemon.fish: XDG_DATA_DIRS: .profile/share

It seems reasonable to add the `share` folder from the user profile into
`$XDG_DATA_DIRS` both for daemon and profile execution.  Nix could add
package shared files into this folder regardless of how the nix daemon
itself is running.

Author: ilya-bobyr

scripts/nix-profile-daemon.fish.in

@@ -21,14 +21,21 @@ function add_path --argument-names new_path
 end
 
 # Main configuration
+
+# Set up the per-user profile.
+
+set NIX_LINK $HOME/.nix-profile
+
+# Set up environment.
+# This part should be kept in sync with nixpkgs:nixos/modules/programs/environment.nix
 set --export NIX_PROFILES "@localstatedir@/nix/profiles/default $HOME/.nix-profile"
 
 # Populate bash completions, .desktop files, etc
 if test -z "$XDG_DATA_DIRS"
     # According to XDG spec the default is /usr/local/share:/usr/share, don't set something that prevents that default
-    set --export XDG_DATA_DIRS "/usr/local/share:/usr/share:/nix/var/nix/profiles/default/share"
+    set --export XDG_DATA_DIRS "/usr/local/share:/usr/share:$NIX_LINK/share:/nix/var/nix/profiles/default/share"
 else
-    set --export XDG_DATA_DIRS "$XDG_DATA_DIRS:/nix/var/nix/profiles/default/share"
+    set --export XDG_DATA_DIRS "$XDG_DATA_DIRS:$NIX_LINK/share:/nix/var/nix/profiles/default/share"
 end
 
 # Set $NIX_SSL_CERT_FILE so that Nixpkgs applications like curl work.
@@ -56,7 +63,8 @@ else
 end
 
 add_path "@localstatedir@/nix/profiles/default/bin"
-add_path "$HOME/.nix-profile/bin"
+add_path "$NIX_LINK/bin"
+set --erase NIX_LINK
 
 # Cleanup